"""The objective of this contract is to provide synthesis of selected chemical carcinogens, derivatives of polynuclear aromatic hydrocarbons (PAH) and chemopreventive agents in support of the Cancer Etiology Branch located within the Divison of Cancer Biology at the National Cancer Institute. The Cancer Etiology Branch (CEB) supports research programs dealing with biological, chemical, and physical agents that are known or possible etiological factors or co-factors in cancer. "